Research On Detection Performance Of Physical-layer Network Coding Signals With Continuous Phase Modulation

In recent years, wireless communication enjoys rapid development due to its strong adaptability, fast network building, wide range coverage and so on. With the novel concept of physical-layer network coding coming into being, wireless communication has achieved a great breakthrough in throughput. But recent studies on physical-layer network coding are almost about linear modulation modes, such as BPSK, QPSK, QAM and so on. As a matter of fact, the huge channel fading along with the urgent demand for faster and faster transmitting speed makes linear modulations not the best option for wireless communication which is strict about power and spectrum utilization efficiency. As a result, continuous phase modulation(CPM) has been brought into the limelight because of its high power and spectrum efficiency.The paper firstly discusses the coherent detection of CPM signals in physical-layer network coding(CPM-PNC), giving simulation results and analysis of two particular CPM signals. However, coherent detection involves complex phase synchronization. In addition, the synchronization error can greatly affect the performance and stability of the detection. To tackle this problem, a noncoherent multiple-symbol detection algorithm for CPM-PNC is proposed. The proposed algorithm is robust to phase-offset and is effective to narrow its performance gap with coherent detection of CPM-PNC by making full use of the inherit memory of CPM. Although the proposed noncoherent multiple-symbol detection algorithm exhibits superior performance, the detection efficiency is a problem. In order to improve the detection efficiency, the noncoherent block detection algorithm for CPM-PNC is proposed. In contrast with the noncoherent multiple-symbol detection algorithm, the noncoherent block detection algorithm can detect a group of symbols at one time, which greatly enhances the detection efficiency. Furthermore, the low-complexity CPM-PNC noncoherent block detection and modified CPM-PNC noncoherent block detection algorithms are also proposed to tackle the complexity and performance problem. The proposed low-complexity CPM-PNC noncoherent block detection algorithm turns out to be an efficient way to reduce the complexity of the receiver and the modified CPM-PNC noncoherent block detection algorithm can not only reduce the complexity of the receiver but also improve the detection performance.